Determining the indices of a mesh
To activate the indices at blender 2.79, you type in the python console the following command

bpy.app.debug = True



Switch to the 3D view and press N to access the Mesh display where the indices icon is activated



Finally, you would have the indices appear on the mesh



For who is interested in for more details: these indices would be used to located where the constraint are added to the volumetric mesh in physical simulation like SOFA physics engine simulator

This how it looks like, this would facilitate adding a constraint for a volumetric mesh in a physical simulation like SOFA framework.

this how it looks like in the XML​ code:

&lt;FixedConstraint template="Vec3d" name="Fixed Dofs" indices="12 15 28 31" drawSize="0" /&gt;